Vets disappointed by low rate of Hendra virus vaccination

It was touted as one of the most successful vaccination breakthroughs in recent times, but the take up of the vaccine against the potentially deadly Hendra virus has been disappointingly slow. Experts now fear human health could be at risk, as Cathy Pryor reports.

When two Queensland vets died within months of each other in 2008 and 2009 from two separate cases of the deadly Hendra virus, the disease grabbed media headlines. Here was a virus, of which there was no known treatment, transferring from horses to the people who were trusted with their care. Just two years later, cases of Hendra spiked. There were 18 outbreaks and 24 horses infected in 2011 alone and, for the first time, a dog tested positive to the virus.

The CSIRO poured millions of dollars into a vaccine which was finally commercially released by drug company Pfizer Animal Health (now Zoetis) in November 2012. Eighteen months later, however, only a small number of horse owners—an estimated 11 per cent nationwide—have vaccinated their horses, and vets and authorities are increasingly worried.

The cost of a full course of vaccination is probably less than the cost a fancy browband for your show horse. I think it's cheap compared to the risk you are taking if you don't.

Dr Frank Condon, vet

The concern is particularly acute in Queensland and NSW, the two states that have been affected by the virus so far. The disease is named after Hendra, the Brisbane suburb where the first known death in Australia occurred in 1994: prominent horse trainer Vic Rail. The virus is believed to spread to humans who come into contact with the bodily fluids of infected horses, who in turn catch the virus from flying foxes. There is no commercial vaccination for humans; advice from both the Queensland and NSW authorities is that the vaccination of horses is the best way to prevent a Hendra outbreak.

Earlier this month, a horse in the Beenleigh area of Queensland had to be euthanased when it tested positive to the virus, the second case in the state this year. Another two horses on the property are still being monitored for the virus and the property remains quarantined.

In announcing the most recent case, Queensland Health said it was standing by 'to offer assistance, counselling, information, testing or treatment' to any person affected if required. Authorities also revealed the infected horse had not been vaccinated against the virus.

Dr Frank Condon is president of Equine Veterinarians Australia and has a vet practice on the Atherton Tablelands in far north Queensland. He is angered by what he believes is a blinkered approach to the problem by horse owners around the country, who he says have been 'recalcitrant' on the issue. The low vaccination rate is putting vets at risk, as they are more likely to come into contact with the virus while treating a sick horse. Some vets are now refusing to treat horses that have not been vaccinated against the disease or refuse to see horses altogether.

Dr Condon has not taken that stance yet, but he holds concerns for his young staff who are sent out to treat sick horses. Although his vets use protective gear if there is any doubt, Dr Condon says his own wife is not happy with the fact he could one day be treating a Hendra infected horse.

'I get a bit frustrated that horse owners aren't taking it more seriously,' he says. 'We are assuming the risk from them.'

'The main concern is that every sick horse and even horses that are well that are carrying the disease, or about to break out in the disease, can still shed the virus ... so with every horse we have concerns this could be a Hendra case, so it is incredibly stressful.'

One of the reasons given by horse owners who have not vaccinated their animals is the high cost of the drug. A vet must administer it and they choose how much to charge for both the vaccine and the call out. It typically costs between $120 and $180 for two initial doses, three to six weeks apart. However, industry sources acknowledge there have been cases of some vets charging well over $200 per dose.

There is also a booster required six months after the initial dose and every six months after that. If you own more than one horse, the costs can mount up. The industry is hopeful that soon the Australian Pesticides and Veterinary Medicines Authority, the government agency which regulates vaccines, will approve an extension of the period before each booster is required, from six months to a year.

Kent Wells is a stock horse stud owner and the head of the Horse Industry Alliance of Queensland. He owns around 45 horses and says he has not vaccinated against Hendra because of the cost. Mr Wells says he has weighed up the risks and believes he is doing enough to protect his horses by keeping those in the paddock away from trees that might harbour fruit bats, and by housing the rest in stables.

'We simply cannot afford [to vaccinate],' he says.

'We find that with anyone who has any more than three to five horses, cost is the issue. We've had a huge uptake in our members of the small horse owners, but above that, it's an expense issue.'

It is not just the cost that is preventing some owners from vaccinating, though. Some have expressed concern that some countries, such as the United Arab Emirates, will not purchase horses which have been vaccinated against Hendra because the antibodies are still present in their system. Others fear the vaccine is not safe to be administered to pregnant broodmares.

Zoetis, however, says concerns about the effects the vaccine might have on broodmares are ill founded. The company says the drug was not initially registered to be used on pregnant mares because of the urgency of getting it onto the market. However, a study is currently underway on the subject and there is no evidence to suggest there is any additional risk to pregnant mares.

The company also says it is hopeful that the UAE and China will change their position on importing Hendra vaccinated horses, just as Hong Kong and Singapore have. Sources say part of the problem is that there is no test that can differentiate between a horse with the disease and one that has Hendra antibodies because of the vaccination. However, Zoetis says all horses vaccinated against the virus in Australia are recorded on a registry so proof of vaccination is readily available.

Zoetis has clearly been frustrated with the slow take up of the vaccine. In March last year its general manager, Mike van Blommestein, said that if sales did not improve the situation might get to a point where the company decided it was not commercially viable to continue manufacturing the vaccine. The company had since retracted the comments and production is assured, according to an industry source.

Even some horse owners are frustrated at the slow take up. Rob Kerslake is the president of the Queensland Horse Council and breeds Irish draft horses. He says it is a shame that millions were poured into finding a vaccine for Hendra, only for the horse industry to drag the chain. He says he has vaccinated all of his nine horses, despite the cost, and would urge others to do the same.

'I have young kids riding horses, interacting with them, and I felt it was too great a risk,' he says.

'We certainly live in an area where there are a number of fruit bats ... so I thought the risk was far too great.'

Dr Condon believes that cost is simply an excuse that doesn't stack up. He says horse owners in Australia are slow to vaccinate against other diseases such as tetanus, a practice which is commonplace in Europe and the USA. Some organisations, such as the Ekka agricultural show in Brisbane, now refuse to accept horses that have not been vaccinated against Hendra. Dr Condon believes this is the only way attitudes will change.

'The cost of a full course of vaccination is probably less than the cost of two shoeings, it's probably less than the cost of a fancy browband for your show horse,' he says.

'Yes, it can be expensive, but I would argue how much money do you place on your child's life or your veterinarian partner's life? I think it's cheap compared to the risk you are taking if you don't do it.'